org.apache.hadoop.hive.ql.lib.TypeRule Maven / Gradle / Ivy
/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.hadoop.hive.ql.lib;
import java.util.Stack;
import org.apache.hadoop.hive.ql.parse.SemanticException;
/**
* Rule that matches a particular type of node.
*/
public class TypeRule implements Rule {
private Class nodeClass;
public TypeRule(Class nodeClass) {
this.nodeClass = nodeClass;
}
@Override
public int cost(Stack stack) throws SemanticException {
if (stack == null) {
return -1;
}
if (nodeClass.isInstance(stack.peek())) {
return 1;
}
return -1;
}
@Override
public String getName() {
return nodeClass.getName();
}
}